Jakob Dörr is a PhD student at the University of Bergen, working with Marius Årthun in the BCPU research area on “Understanding mechanisms for climate predictability”. In the spring of 2022, he travelled to California, to visit Dave Bonan. For four weeks, Jakob had the opportunity to work with Dave and his working group at the California Institute of Technology (Caltech) in Pasadena. Dave is also a PhD student, and also interested in understanding present and future changes in the Earth’s sea ice cover, and which processes these are caused by.
In the Arctic, the sea ice cover has strongly declined in all seasons over the last 40 years, and this is mostly due to the Earth’s warming, driven by anthropogenic greenhouse gas emissions. However, because the sea ice interacts with the ocean and the atmosphere and is thus part of the chaotic climate system, it is affected by random fluctuations and internal variability which is independent from the long-term warming trend. These variability modes can affect the sea ice for periods of up to several decades. It is therefore not entirely clear exactly how much of the sea ice loss we have observed over the last decades was due to global warming, and how much was because of internal variability. Dave and Jakob are working to detect and separate those variability modes that affect the sea ice over long periods (decades and longer) in the observational record of sea ice. They use a novel technique developed by Robb Wills at the University of Washington.
Jakob and Dave are hoping to determine for different regions of the Arctic, which modes of variability affect the sea ice cover, and how much their influence compares to the long-term sea ice loss due to global warming. This will help to understand and attribute past sea ice changes and enhance our ability to predict the future regional sea ice loss. While Jakob focuses on the Arctic, Dave applies the same technique to the Antarctic, where a steady increase in sea ice cover over the last decades, followed by a strong decline since 2016, has been observed. Their analysis might shed some light on the mechanisms behind this puzzling evolution, and how much of it was caused by changes due to global warming. The goal of the BCPU-supported visit was to prepare work for two separate publications on Arctic and Antarctic sea ice, respectively, and to discuss how experience from observations can be applied to analyse climate model simulations of future sea ice change.
“During the visit, we exchanged our experience and discussed new ideas for our analysis. I also got to meet scientists in both the Oceanography (Andrew Thompson) and the Climate Dynamics (Tapio Schneider) group at Caltech. I was also lucky to come at a time where Caltech was opening fully again, with many international scientists visiting the institute. Furthermore, I got invited to be part of a sea ice reading course where we had intense discussions about sea ice models, trends and mechanisms with Dave and other members of the Oceanography group. On top of that, I had the chance to visit some friends from the Scripps Institute of Oceanography in San Diego. I had a lot of interactions during the visit and learned a lot about how science is conducted at Caltech and other US institutions. I hope that I can continue the collaboration between Caltech and the Bjerknes Center beyond our work on sea ice observations. The visit showed me how important it is to physically meet people to exchange ideas and develop collaborations across the globe. There are plans that Dave visits us in Bergen next spring, and I hope to return to Pasadena after that.” – Jakob Dörr
Check out this nice article by Dr. Ellen Viste at the Bjerknes Centre for Climate Research, on the evaluation of sea ice models and how far we are to being able to provide reliable, near-term sea-ice predictions:
In it, we hear from Tarkan Bilge, our BCPU data manager, and his recent paper on sea ice thickness forecasts to support Arctic marine transport, together with other collaborating scientists at our partner, NERSC, among others.
On January 31st 2022, the Bjerknes Centre for Climate Research received Espen Barth Eide, our minister for Climate and the Environment, for a visit. On this occasion, Dr. Helene Langehaug gave a talk about the role of the ocean in improving climate predictions, which is a crucial aspect the Bjerknes Climate Prediction Unit’s research work, towards improving predictions from seasons to several years ahead.
Find out more about our research areas and results, or just get in touch with our team.
The proceedings of our “Multi-annual to Decadal Climate Predictability in the North Atlantic-Arctic Sector” workshop, 20-22nd September 2021, jointly organized by the Bjerknes Climate Prediction Unit, Blue-Action, ROADMAP and CLIVAR, are now available. Check this page for links and resources: blue-action.eu/events/predictabilityworkshop
This workshop will explore the importance of the ocean in the global and north west European climate, the need to ensure we are measuring the strength of ocean currents and the ocean’s properties, and how this information can be incorporated into climate models, climate services and decision-making at national and international levels.
Bee Berx (Scottish Government)
Mark Payne (Danish Meteorological Institute)
Jacob Høyer (Danish Meteorological Institute, GHRSST Group for High Resolution Sea Surface Temperature)
Noel Keenlyside (Bjerknes Centre for Climate Research, University of Bergen)
Marit Reigstad (UiT the Arctic University of Norway)
Siân Henley (University of Edinburgh)
Finlo Cottier (Scottish Association for Marine Science)
Organizer: Scottish Government with the Danish Meteorological Institute, Bjerknes Centre for Climate Research, UiT the Arctic University of Norway, University of Edinburgh, Scottish Association for Marine Science
Online access to all events
No accreditation to COP26? Don’t worry. All events will be streamed by our media partner, We Don’t Have Time. Follow this event live on their COP26 streaming hub:
Tor Eldevik leads EASAC report, “A sea of change: Europe’s future in the Atlantic realm”.
In the report an international panel of experts goes through the changes seen until now in the Atlantic Ocean, and what we can expect of climate change. But there is also a potential in being the closest neighbour to our western ocean.
The report shows how fluctuations and trends in the Atlantic Ocean affects the climate in Europe and both the environment and resources in the ocean and on land.
“The report is very clear about future climatic risks, but equally focuses on the future benefits we can harvest from better understanding of the relations between the state of the Atlantic and climatic conditions over Europe that affects everything from the supply of renewable energy to fisheries,” says Tor Eldevik.
He emphasises how this knowledge can be used far better than it is now. Climate predictions developed today have the potential to predict cod movements between years, including movements out of Norwegian fisheries sectors.
To power companies the knowledge of how westerlies in the Atlantic Ocean (NAO index) affect Norwegian hydro power production can also be useful.
Tor Eldevik points out how future changes in the ocean are connected to how successful we are at mitigating global warming.
“If we succeed in keeping the average warming to 1.5°C, then Antarctica may continue melting at current rates; but overshooting the 2 °C Paris Agreement target towards 3°C may lead to Antarctic melt alone add 0.5 cm a year by 2100,” he says.
Sea level rise have regional differences, but to the many million people living by the North Sea Basin, accounting for a meter rise in sea level.
Cities along the coast of the Netherlands, Germany, Denmark and Great Britain will be affected greatly.
Central points in the report
Sea level rise
On average, the sea level has risen 11-16 centimeters in the twentieth century.
Europe must prepare for up to one meter sea level rise by 2100. Storm surges on a level we now expect every 100 years, could be yearly by 2100 if CO2 emissions continues as today. Ice melts on Greenland and the Antarctic contributes to sea level rise, as well as glacial metling in warmer areas and sea water expanding with heat. There is uncertainty linked to melting on Greenland and the Antarctic which needs to be followed closely.
Wind, weather and precipitation over Europe, and especially the Norwegian coast, kan be linked to the ocean. The strength of the Gulf Stream and the westerlies over the Atlantic Ocean affects the severity of wind and precipication over Europe, including the Norwegian coast. This knowledge is critical to predict climate fluctuations for the coming years and seasons – which in Norway is especially useful to power companies, both wind and hydro energy production.
Temperature increases leads to fish stocks moving, uptake of CO2 makes the ocean more acidic, which changes the living conditions for life in the ocean. If the current emissions of climate gases is kept up, we will reach a level in 2100 that is uninhabitable.
Ocean circulation, ocean streams and the Gulf Stream giving us a milder climate
Speculations that the Gulf Stream will stop are excessive. But the Gulf Stream strength are connected to climate in Europe and Norway. A decline in heat transportation of 20% is expected further South in the Atlantic this century, but as far North as Norway we are likely to see an increase in the stream and a continued heating of the ocean.
Side event at the All Atlantic Conference 2021, where climate forecasting on a broad level was discussed. BCPU has contributing members in the EU Horizon 2020 projects TRIATLAS and Blue Action, who were organising the event with projects AtlantECO and Mission Atlantic.
Watch the presentations and following discussion on Youtube:
Hver dag i desember la Bjerknessenteret ut en video med en av senterets klimaforskere.
Helene Langehaug er forsker ved Bjerknessenteret og Nansensenteret for miljø- og fjernmåling, og jobber blant annet i Bjerknes Climate Prediction Unit. Hun er en av dem på Bjerknessenteret som lenge har jobbet med klimavarsling. For å kunne gjøre det, er havet ekstra viktig. Det er havet som er klimaets hukommelse, og som legger mye av grunnlaget for å se lengre frem enn det værvarslingen for øyeblikket kan gjøre.